Motor fuel composition



3,365,283 MDTQR FUEL QDWPGSTTTGN Edwin C. Knowles, Poughkeepsie, George W. Eclrert, Wappingers Falls, and Frederic C. McCoy, Beacon, NR1, assignors to Texaco inn, New York, N. a corporation of Delaware No Drawing. Filed Dec. 19, 1963, Ser. No. 331,9ll 9 Claims. ((Il. 44-69) This invention relates to a hydrocarbon fuel composi tion having excellent surface ignition properties. More particularly, the invention relates to a leaded gasoline containing a combustion chamber deposit modifier which reduces surface ignition and other harmful effects brought about by the formation of deposits in the combustion chamber of a gasoline engine.

Most conventional gasolines contain an alkyl lead compound, such as tetraethyl lead or tetramethyl lead as an anti-knock compound to improve the octane level of the gasoline. During combustion, alkyl lead compounds break down to lead oxide and lead salts and form deposits in the combustion chamber of the engine. The lead deposits, which are characterized by a low ignition temperature, become incandescent at engine operating temperatures interfere with proper engine operation. Specifically, the glowing or incandescent deposits cause premature firing of the fuel-air mixture during the compression stroke of the combustion cycle resulting in uneven firing in the engine with concomitant loss of power and an audible rumble noise. This phenomenon is known as surface ignition. Combustion chamber deposits also seriously educe the efficiency of the sparkplugs even to the point of causin them to mis-fire completely. This is a serious defect particularly in the case of a leaded gasoline for aircraft operation.

The formation of lead deposits in gasoline engines has been greatly reduced by employing scavenger agents in conventional leaded gasoline. Scavenger agents are compounds capable of reacting with the tetraalkyl lead compounds during combustion to produce volatile lead compounds. The principal scavengers in use are alkylene dihalides, such as ethylene dichloride, ethylene dibromide and their mixtures. These compounds brin about the formation of lead chloride and lead bromide which, being volatile, are substantially removed from the engine during the exhaust cycle. Unfortunately, minor amounts of the lead compounds remain deposited in the engine creating a surface ignition problem which is particularly serious for modern high compression engines.

Considerable research has been conducted to reduce or overcome the surface ignition problem caused by combustion chamber deposits. This has led to the discovery of certain phosphate esters which are effective in reducing surface ignition. indeed certain aryl phosphate esters have achieved some degree of commercial acceptance. The known phosphate esters, however, have harmful side effects on gasoline. A major objectionable feature of these phosphate esters is that they lower the octane value of gasoline, a particularly serious drawback where ones object is to produce the highest quality gasoline on a competitive basis.

The present invention provides a leaded gasoline containing a minor amount of a reaction product which exhibits an outstanding improvement in surface ignition properties. Striking advantages of the invention are the fact that the surface ignition suppressor has no harmful or deleterious effect on the overall octane quality of the gasoline and that the additive is more effective for reducing surface ignition than some commercially available phosphate esters.

The motor fuel of the invention comprises a mixture of hydrocarbons in the gasoline boiling range containing a united States Patent 0 F ice minor amount of an organo-lead anti-detonant and from about 0.01 to 1.0 theories of an oil-soluble nitrogenphosphorus containing reaction product. The nitrogenphosphorus-containing reaction product is produced by reacting certain primary or secondary amines with phosphorus pentoxide under suitable conditions as described more fully hereinbelow.

Primary and secondary amines which are effective when reacted with phosphorus pentoxide to form the reaction product of this invention are represented by the formula:

in which R is a hydrocarbyl radical having from 8 to 30 carbon atoms, 1: is an integer from 1 to 2 and the sum of n and m equals 3. R is generally an alkyl radical and, more desirably, a branched chain alkyl radical because of the ready availability of these materials. Preferably, R is a tertiary alkyl radical having from 12 to 30 carbon atoms.

Examples of suitable primary and secondary amines include laurylamine, 2-ethy1hexylamine, tridecylarnine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine, tricosylamine, methyldodecylamine, methyloctadecylamine, and the like. Particularly preferred amines are certain commercially available mixtures of tertiary alkyl primary amines. For example, a mixture of tertiary alkyl primary amines in which the alkyl radical comprises a mixture of alkyl groups having from 11 to 14 carbon atoms is available under the name Primene 81-R. Another commercially available amine is a mixture of ter tiary alkyl primary amines in which the alkyl radical comprises a mixture of alkyl groups having from 18 to 24 carbon atoms sold under the name Primene IMT.

The reaction between the above-defined amine and phosphorus pentoxide is effected using amine to phosphorus pentoxide mole ratios in the range of 2:1 to 4:1 respectively. The reaction products can be prepared by intimately mixing the compounds together. Preferably, the reaction is effected by formin a slurry of phosphorus entoxide in a hydrocarbon solvent such as benzene or toluene followed by gradual addition of the amine to the stirred slurry with cooling if necessary. The reaction mixture is heated for several hours to complete the reaction at about the reflux temperature of the solvent, at temperature of 8590 C. generally being satisfactory. The reaction mixture can be added directly to gasoline although it is often desirable to filter the reaction mixture and strip off the solvent to recover the reaction product.

it is essential that the reaction product be oil-soluble. By oil solubility is meant solubility in a motor fuel in the gasoline boiling range. This is accomplished by employing only amines in which the hydrocarbyl radical represented by R has at least 8 carbon atoms as defined above and by employing these amines in such proportions that the reaction product contains at least 24 hydrocarbyl carbon atoms per mole of phosphorus pentoxide reacted.

The reaction product of the invention is added to a motor fuel containing a conventional anti-knock compound. The base fuel itself may consist of any hydrocarbon fuel including parafiinic naphthenic and aromatic hydrocarbons or mixture thereof suitable for use in an internal combustion spark ignition engine. The base fuel fractions can be derived by the distillation of crude oil, by the catalytic or thermal cracking of gas oils, by the alkylation of isoparafiins with olefins or by the polymerization of olefins. The boiling point of the motor fuel or gasoline will generally be in the range from about F. to about 400 F. The motor fuel of the invention Will contain a tetraalkyl lead compound, such as tetraethyl lead, in a concentration from about 0.5 cc. to about 4.6 cc. or more per gallon of fuel. This motor fuel can also contain additives conventionally employed in gasoline,

such as scavengers, anti-oxidants, stabilizers, dyes and the like.

The amount of the nitrogen-phosphorus-containing reaction product of the invention employed in gasoline is expressed in terms of theories based on the phosphorus content of the reaction product. One theory of the nitrogen-phosphorus-containing reaction product is defined as the amount which provides sufiicient phosphorus to react stoichiornetrically with the lead atoms in the tetraalkyl lead compound present to form the compound Pb (PO The reaction product of the invention is blended into the leaded gasoline in a concentration ranging from about 0.01 theories to about 1.0 theories in accordance with the afore-going definition. A concentration between about 0.05 and 0.6 theories is in the preferred range for the surface ignition suppressor of the invention.

The following examples illustrate the preparation of the nitrogen-phosphorus-containing reaction products of the invention.

Example I 17.7 grams (0.125 mole) of phosphorus pentoxide was added to 100 ml. of benzene forming a slurry. 158 grams (0.5 mole) of Primene JM-T was very gradually added to the stirred slurry with cooling of the reaction vessel to control the temperature of reaction. After all of the Primene JM-T had been added, the mixture was brought to a temperature of 8590 C. and maintained at this temperature for about two hours. The reaction mixture was stripped of benzene and filtered. The recovered reaction product had the following properties:

Nitrogen (4.0 theory) percent 3.89 Phosphorus (4.4 theory) do 4.5 Spec. gravity, 60/60 F 0.9308 Ref. index, 25 C. 1.4724

Example 11 17.7 grams (0.125 mole) of phosphorus pentoxide was added to 100 ml. of benzene to form a slurry. 120.5 grams (0.5 mole) of di-Z-ethylhexylamine was gradually added and reacted using the procedure described in Example I above. The recovered reaction product had the following properties:

Nitrogen (5.1 theory) percent 5.13

Phosphorus (5.6 theory) do 6.3

Spec. gravity, 60/60 F. 0.9242

Ref. index, 25 C 1.4607

Example III 35.5 grams (0.25 mole) of phosphorus pentoxide was added to 78 grams of benzene forming a slurry. 120.5 grams (0.5 mole) of di-Z-ethylhexylamine was gradually added to the stirred slurry with cooling of the reaction vessel to control the temperature during the initial reaction. After the di-Z-ethylhexylamine had been added, the mixture was reacted for about 2 hours at a temperature in the range of 85-90 C. The reaction mixture was filtered and a portion thereof stripped of benzene to recover the reaction product.

The reaction product had the following properties:

Nitrogen (4.5 theory) "percent" 4.2

Phosphorus (9.9 theory) do 10.4

Spec. gravity, 60/60 F 1.014

Ref. index, 120 F 1.436

Example IV 35.5 grams (0.25 mole) of phosphorus pentoxide was added to 68 grams of benzene to form a slurry. 100 grams (0.5 mole) of Primene 81-R was gradually added and reacted using the procedure described in Example III above. The recovered reaction product had the following properties:

Nitrogen (5.2 theory) "a percent 5.05

Phosphorus (11.5 theory) do 10.56

Spec. gravity, 60/60' F 1.043 Example V The reaction products of the invention were tested for their effectiveness in a single cylinder CFR L-head engine with an 11.3/1 compression ratio. The engine was continuously run on the test fuel over a 20-hour test period during which time engine operation was alternated be tween a SO-second idle cycle (600 r.p.m.) and a second full throttle cycle (900 r.p.m.). The surface ignition count rate was obtained using an ionization gap (sparkplug) as the surface ignition pickup coupled to a recording counter device. The surface ignition rate is expressed as the uumber of counts per hour, the lower the count value the better the performance of the fuel.

The tests were conducted using a high octane blended gasoline as the motor fuel. This gasoline containing 40 percent aromatic hydrocarbons boiled in the range of 85 F. 113? to 376 F. ER, had a research octane number of 101.5, and contained 3 ml. of TEL per gallon.

The reaction products from the foregoing examples were blended into the leaded gasoline to provide phosphorus in the amounts indicated as theories of phosphorus according to the definition given above. The results of these tests are given in the following table.

TABLE I.-SURFACE IGNITION Reaction Product Fuel plus Indicated Reaction Product Concentration Counts per hr.

in Theories Leaded Base Fuel 495 Example I 0. 6 33 Example II 0. 6 28 Example III 0.3 Example IV 0. 6 57 Monocresyl (liphenyl phosphate 0.3 213 0. 6 119 0. 3 "210 0. 8 T5 The reaction products of the invention produced an outstanding improvement in surface ignition in comparison to commercial arylphosphate esters, namely tricresyl phosphate and monocresyl diphenyl phosphate. Tests also showed that this improvement was obtained without any loss or reduction in the octane value of the gasoline.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A motor fuel in the gasoline boiling range containing an organo-lead anti-detonant and from about 0.01 to 1.0 theories of an oil-soluble nitrogen-phosphorus-containing reaction product produced by reacting at an elevated temperature an amine with phosphorus pentoxide in a mole ratio of 4:1 to 2:1 respectively, said amine being represented by the formula:

R NH

in which R is a hydrocarbyl radical having from 8 to 30 carbon atoms, 11 is an integer from 1 to 2 and the sum of n and m equals 3.

2. A motor fuel according to claim 1 containing from 0.05 to 0.6 theories of said reaction product.

3. A motor fuel according to claim 1 in which said amine is a branched-chain primary alkyl amine having from 12 to 30 carbon atoms.

4. A motor fuel according to claim 1 in which said reaction product is produced by reacting a C1844 alkylarnine with phosphorus pentoxide.

5. A motor fuel according to claim 1 in which said reaction product is produced by reacting a C1144 alkylamine with phosphorus pentoXide.

6. A motor fuel according to claim 1 in which said reaction product is produced by reacting di-2-ethylhexylamine with phosphorus pentoxide.

7. A motor fuel according to claim 1 containing from about 0.5 to 4.6 cc. of an organo-lead anti-detonant.

8. A motor fuel according to claim 7 in which said organo-lead anti-detonant is selected from the group consisting of tetraethyl lead and tetramethyl lead.

9. A motor fuel composition according to claim 1 in which the mole ratio of said amine to said phosphorus pentoxide is about 2:1 respectively.

6 References Cited UNITED STATES PATENTS 2,863,743 12/ 1958 Pellegrini et a1 4472 X 2,999,739 9/1961 Heron 4469 3,004,838 10/1961 Larson 44-69 OTHER REFERENCES G. M. Kosolapoff, Organophosphorus Compounds, page 259 1950).

PATRICK P. GARVIN, Primary Examiner. DANIEL E. WYMAN, Examiner.

W. J. SHINE, Assistant Examiner. 

1. A MOTOR FUEL IN THE GASOLINE BOILING RANGE CONTAINING AN ORGANO-LEAD ANTI-DETONANT AND FROM ABOUT 0.01 TO 1.0 THEORIES OF AN OIL-SOLUBLE NITROGEN-PHOSPHORUS-CONTAINING REACTION PRODUCT PRODUCED BY REACTING AT AN ELEVATED TEMPERATURE AN AMINE WITH PHOSPHORUS PENTOXIDE IN A MOLE RATIO OF 4:1 TO 2:1 RESPECTIVELY, SAID AMINE BEING REPRESENTED BY THE FORMULA: 